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9
votes
4answers
1k views

Can a file that was originally sparse and expanded be made re-sparse

I know that copying or transferring what was originally a sparse file without using a utility that understands sparse files will cause the 'holes' to be filled out. Is there a method or utility to ...
19
votes
4answers
7k views

Clone whole partition or hard drive to a sparse file

I like to clone a whole partition or a whole hard drive onto a larger external disk but like to create a sparse file. I often use dd for cloning, but it doesn't support sparse files. As a workaround I ...
8
votes
2answers
1k views

Detailed sparse file information on Linux

I have a sparse file, in which only some blocks are allocated: ~% du -h --apparent-size example 100K example ~% du -h example 52K example I would like to know which blocks of the file are ...
4
votes
1answer
1k views

Sparse files/file holes and unexpected block size

For my own learning, I've been playing around with creating files with file holes. I created a util that simply reads from stdin and writes to a file, but before writing to the file, it uses lseek to ...
2
votes
1answer
535 views

Can QEMU/KVM+OCFS2 be configured to punch holes in sparse image files when files are deleted in the guest?

I'm using sparse raw image files for guest VMs and OCFS2 on the host (local-only, not clustered) for the reflink feature. I understand from Googling around that OCFS2 is one of the filesystems that ...
4
votes
3answers
527 views

from a sparse file to a block device over the network

If I have a sparse file representing a block device, then how can I efficiently restore the file over a network? Ideally, I'd use rsync -S host:file /dev/sdb, but rsync won't write to block devices. ...